1. Field of the Invention
The present invention relates to a method and device for determining the position of an element possibly immersed in a liquid medium.
With the present invention two elements possibly immersed in a liquid medium can be placed in a given relative position.
For example, work carried out at the bottom of the sea, it may be necessary to place two separate elements at a given relative position, more particularly for connecting them together (see French Pat. No. 2 136 291). These elements may be two pipes which are to be connected end to end, or else a pipe and an immersed structure, such as a well or an immersed manifold of the oil manifold type, etc . . . .
2. Description of the Prior Art
These operations, already difficult to carry out when they are effected under the direct control of divers, raise problems when "robots" are used which are equipped with at least one television camera and lighting equipment. In this case, the operator who is at the surface visually controls the assembly operations and accordingly controls the manipulating arms of the robot.
This solution, besides its high cost, has drawbacks which result from the fact that the space controlled visually by the operator is of relatively small dimensions. In fact, the lighting at most only provides vision in a space of a few meters in diameter, often not exceeding two meters. This optical field is often obscured by loose sediments at the bottom of the sea which are stirred up by movement of the water following movement of the parts to be assembled. In some cases, the optical field is is completely obscured. Finally, the accuracy of assembly is limited by the fact that very often the operator only has a two dimensional image for visual control.